1. Field of the Invention
The present invention relates to magnets that are used to remove metal cuttings, metal shavings, metal parts, and like metallic material from a flow stream of oil well drilling mud. More particularly, the present invention relates to an improved method and apparatus for removing metal cuttings, metal shavings, metal parts and the like from an oil well drilling mud flow stream wherein a magnetized bar has first and second end portions, each carrying an end plate and wherein a non-magnetic wiper plate attaches to the magnetized bar in between the end plates, the wiper plate being slidable upon the magnetized bar between the end plates so that movement of the wiper plate from one end plate to the other end plate enables removal of the metal cuttings from the magnetized bar.
2. General Background of the Invention
Magnets have been used to remove metal from a flow stream of oil well drilling mud. Examples of commercially available magnets can be seen at the Stacey Oil Services, Ltd. website (www.staceyoil.com) and the Ceesan website (www.ceesan.net). Such magnets are also known in the industry as “ditch magnets”. Some patents have issued for ditch magnets. One such patent is U.S. Pat. No. 3,498,455. Other possibly relevant patents are listed chronologically in the following table.
TABLEPAT. NO.TITLEISSUE DATE2,792,115Magnetic SeparatorMay 14, 19573,498,455Ditch MagnetMar. 30, 19703,713,499Method and Apparatus for TreatingJan. 30, 1973Drilling Mud4,030,558Wear Determination of DrillingJun. 21, 1977Bits5,944,195Method for Separation of SolidsAug. 31, 1999from Drilling Fluids by MagneticSeparation and Centrifugation6,354,386Apparatus for Retrieving MetalMar. 12, 2002Objects from a Wellbore2006/0016732High Gradient Magnetic SeparatorJan. 26, 20062007/0138103Magnetic Separation in FluidsJun. 21, 2007
Many of the metal parts that are collected by the ditch magnet are pieces that have been cut or shaved and are thus of irregular shape and can have jagged edges, sharp points, or the like. Safety is very important and meaningful in the oil and gas industry today. Cuttings that are collected by a ditch magnet can include sharp edged debris that could possibly cut the hand of a worker who handles the ditch magnet.
Cuttings that have been retrieved from a ditch magnet can provide information that is beneficial to oil and gas well operators. These collected cuttings may indicate casing wear during ordinary drilling operations, pipe wear, or any other factor which may be economically detrimental to the well or production.
Time is an important factor in oil and gas well drilling. The cost of drilling is rising. With drilling, rig rates as expensive as they are, a small part of time saved can equate to significant savings. Oil and gas well drilling rates can be as high as $125,000 to $600,000 per day. Thus, any procedure or apparatus that shortens the time for handling the ditch magnet and/or its debris can be a significant savings in money.